-3

在用户单击提交按钮从选择框中选择一个选项而不是使用javascript的默认值后，我将如何提醒他们这是我的代码

<select id = "Sel">
    <option value ="Song1">default value<br>
    <option value ="Song2">Break on through<br>
    <option value ="Song3">Time<br>
    <option value ="Song4">Money<br>
    <option value="Song5">Saucerful of Secrets
</select><br><br>

继承人我的 javascript 代码我不知道从哪里开始，但这不运行

if(document.getElementByID("Sel").value = "default value")
{
    alert("Pick another option besides default value");
}

谢谢！

4

4 回答 4

0

首先，您的标记不正确..将其更正为

<select id = "Sel">
    <option value ="Song1">default value</option>
    <option value ="Song2">Break on through</option>
    <option value ="Song3">Time</option>
    <option value ="Song4">Money</option>
    <option value="Song5">Saucerful of Secrets</option>
</select><br><br>

然后在表单提交检查为

if(document.getElementById('Sel').value=="Song1")
    return false;

或者

if(document.getElementById('Sel').selectedIndex ==0)
    return false;
于 2012-11-27T18:28:40.767 回答
0 
<script>
     $(document).ready(function() {
        $("#Sel").live('click', function (event) {
        var myval=$(this).val;
        alert(myval);
        });
    </script>   
    <select id = "Sel">
            <option name="opSel" value ="Song1">default value</option>
            <option name="opSel" value ="Song2">Break on through</option>
            <option name="opSel" value ="Song3">Time</option>
            <option name="opSel" value ="Song4">Money</option>
            <option name="opSel" value="Song5">Saucerful of Secrets</option>
        </select>
于 2012-11-27T18:29:16.810 回答
0

您的标记首先是错误的..需要关闭打开选项标签

在更改事件中检查值...如果value is Song1 然后向用户发出警报

HTML

<select id = "Sel">
    <option value ="Song1">default value</option>
    <option value ="Song2">Break on through</option>
    <option value ="Song3">Time</option>
    <option value ="Song4">Money</option>
    <option value="Song5">Saucerful of Secrets</option>
</select>​

Javascript

var elem = document.getElementById('submit');

elem.addEventListener('click', function(){
   var selectElem = document.getElementById('Sel');
   var val = selectElem.value;
    if(val == 'Song1'){
        alert('Select an option!!');
        return false;
    }        
});​

检查小提琴

于 2012-11-27T18:27:17.780 回答
0

尝试这个：

<html>
    <head>
        <script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
        <script type="text/javascript">
            $(document).ready(function() {
                $('#Sel').change(function() {
                    if($(this).val()=="Song1"){
                        alert('bad');
                    }else{
                        alert('good');
                    }
                });
                $('#button-test').click(function() {
                    var bob = $('#Sel').val();
                    if (bob=='Song1'){
                        alert('bad');
                    }else{
                        alert('good');
                    }
                });
            });
        </script>
    </head>
<body>

<select id = "Sel">
    <option value ="Song1">default value</option>
    <option value ="Song2">Break on through</option>
    <option value ="Song3">Time</option>
    <option value ="Song4">Money</option>
    <option value="Song5">Saucerful of Secrets</option>
</select><br>
<br>
<button id="button-test">
于 2012-11-27T18:28:20.843 回答